SAN FRANCISCO — Since 2004, Facebook has said it wants to bring the world closer together. To accomplish that goal, the company has relied mostly on the web and smartphone apps.

But software is no longer enough. On Monday, Facebook introduced a pair of video-calling devices — Portal and Portal Plus — to help expand its reach into people’s living rooms.

Portal and Portal Plus, which have a 12-megapixel camera with high-definition video and artificial intelligence software, can be used to do video chats. The A.I.-powered camera follows users as they move, letting them converse without sitting stiffly. The devices also include Amazon’s Alexa, which people can command to play music or check the weather.

Portal, which has a 10-inch screen, will sell for $ 199, while the other model, with a 15-inch display that can be rotated, will be priced at $ 349. Facebook plans to offer the gadgets on a stand-alone website in time for the holidays, and has a major marketing campaign in the works.

The devices are Facebook’s first major foray into designing, building and selling consumer hardware from scratch. If the Portals are successful, the company could encourage more people to use its social network regularly to keep in touch with friends and family, as well as for apps like Spotify and Pandora.

Yet Facebook’s timing could not be worse. After two years of scandals, it will be marketing Portal and Portal Plus to a skeptical public. Last month, the company also announced asecurity breach that put the accounts of at least 50 million users at risk, while endangering the accounts of numerous third-party apps.

To address privacy concerns with Portal and Portal Plus, Facebook said the products include an electronic kill switch for the front-facing camera, as well as a cover for the lens. In addition, video calls are encrypted, and the camera’s A.I. technology runs on the device itself, not on Facebook’s servers, the company said.

The company said the utility of the devices, which work on a household Wi-Fi connection, would convince people of their importance in a home. The devices are built atop Facebook’s Messenger platform, and the communication software is hooked into a user’s web of Facebook connections. Once Portal is connected to a Messenger account, people can video chat with anyone in their network across devices, be it on Portal, a tablet, a smartphone or a desktop computer.

Facebook is entering a fiercely competitive market. Voice-controlled smart speakers, a category birthed by Amazon in 2015 with its Echo, is small but growing. Last quarter, manufacturers shipped 16.8 million smart speakers, up 187 percent from the same period last year, according to the research firm Canalys. Amazon and Google dominate the smart speaker market in the United States. In China, Alibaba and Xiaomi are quickly gaining traction with sales of their artificially intelligent speakers.

In the last two years, smart speakers have evolved to include screens for videoconferencing, videos and apps. Amazon last year unveiled Echo Show, its first Echo with a display, and Lenovo teamed up with Google this year on a smart screen featuring Google’s Assistant. Google is also expected to release its own smart screen this year.

Instead of building its own virtual assistant three years after Alexa’s debut, Facebook worked with Amazon. Like other Amazon-powered products, Portal can be controlled by speaking the word “Alexa” before a question or a request, like “What’s the weather in San Francisco?” or “Set a timer for 10 minutes.”

Jonathan Collins, a research director for ABI Research, said it was wise for Facebook to collaborate with Amazon. While creating a digital assistant has helped Apple, Google and Amazon make their products look more attractive, there was no clear benefit for Facebook to making one of its own, he said.

“It’s not an obvious link to what they do for people at present,” which is to deepen people’s relationships, Mr. Collins said.

Facebook had worked on hardware previously, though its involvement with Portal goes much deeper and further. In 2013, the company and the manufacturer HTC produced the HTC First, a smartphone that ran on a new Facebook-based operating system. The phone flopped.

The company also sells virtual-reality goggles, which it got into when the start-up Oculus was already building those products. Facebook acquired Oculus in 2014.

Rafa Camargo, Facebook’s vice president who oversees Portal, said that when his team said it wanted to work on a smart home product with a large screen, his peers reacted in disbelief — especially since Amazon and Apple were focused on speakers and not video.

“Everyone was like: ‘You’re nuts. T he whole thing is just about smart speakers and just voice,’” said Mr. Camargo, who joined Facebook about two years ago.

But he said that voice was just one feature of the product and that Facebook could offer customers a different type of experience.

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